Heart surgery is usually performed through an incision in the midline of the chest (median sternotomy) which gives a fair access to the heart and to other organs within the thoracic cavity. However, at coronary by-pass surgery which is becoming a routine operation in industrialized countries, there is a need for opening the chest in an asymmetric way since at this operation one may very often use the internal mammary artery which is an artery running longitudinally along the interior surface of the sternum. In order to dissect this artery, the surgeon must see the inside of the sternum and therefore an asymmetric opening of the thoracic cavity is necessary.
Several retractors for opening the chest in a symmetric way exist and even a few for asymmetric opening have been presented so far. The latter, however, have so far been complicated, expensive and have not opened the chest sufficiently.